Sound reproduction



June 30, 1931. D. G. BLATTNER SOUND REPRODUCTION Filed Feb. 24, 1928 rofrA/Ey Patented June 30, 1931 UNITED STATES PATENT OFFICE DAVID G. LBLATTNER, F BOGOTA, NEW JERSEY, ASSIGNOR TO BELL TELEPHONE LA B- ORATORIES, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK SOUND REPRODUCTION Application filed February 24, 1928.

This invention relates to sound reproducing systems and more particularly to mechanical pick-up devices for reproducing low frequency vibrations such as recorded heart sounds. The general object of the invention is to provide such a device at very low cost.

In accordance with the general features of the invention the pick-up device is held in the hand so that the fingers serve as the pivot of the stylus arm and supply the proper damping action for the vibrating system; the needle arm is attached to a diaphragm of flexible material along its diameter and the :1' sound is heard by means of an ordinary stethoscope attached to the sound box associated with the diaphragm.

In the drawings Fig. l is a general view showing the method of using this invention. Figs. 2 and 3 show in detail the construction of the pick-up device.

The record l to be reproduced is placed upon any available phonograph turntable and the pick-up device is held with set screws 2, which holds the stylus 3 in place, between the thumb and finger as shown. When the stylus 3 is in contact with the moving record, the recorded sounds cause the stylus arm l to vibrate about the pivot pointprovided by the fingers. This arm is attached to a flexible rubber diaphragm 5 along a diameter and the diaphragm in turn is secured to a metal ring 6 which is threaded to receive the sound box 7 as shown in Fig. 3. The movements of the stylus arm alternately compress and release the diaphragm 5 in the usual Way so that air vibrations corresponding to the sounds of interest are produced in the sound box and reach the ears of the operator 8 through the acoustic stethoscope 9. Minor adjustments of the volume level for obtaining a more natural tone may be made by means of the adjustable clamp 10 of any well known type which will be effective to vary the size of the air passage at the clamping point. In the device shown a tubular member 1l surrounds the tube 9 and is threaded to receive the thumb screw l2. A metal strip 13 is bent at its ends to keep it within the member l1 and under the action Serial No. 256,502.

natural volume, relatively free from surface noise andyet be of such a simple construction as to be very inexpensive.

The inertia type construction already described was found to fulfill all of these requirements. The use of a high dissipation material in the diaphragm results in low efficiency particularly at high frequencies. rIliis means that lthe device discriminates against objectionable noise and reproduces the desired sounds at only their natural intensity. vThe flexibility of the diaphragm makes it capable of responding to the low frequency transients and the high degree of damping introduced by holding the device in the hand and driving the diaphragm in the manner shown assures faithfulness of reproduction.

What is claimed is:

l. The combination with a phonograph pick up device adapted to be held in the hand of an operator, of acoustic stethoscopic means for conducting the sound waves set up in the device to the ears of the operator.

2. In a sound box the combination of a casing with a diaphragm of flexible, high dissipation material and a stylus arm secured to said diaphragm along a diameter of said diaphragm.

3. In a sound box the combination with a casing and a thick diaphragm of high dissipation material secured at its periphery to said casing, of a stylus arm adapted to be held in the hand and attached to said diaphragm along a diameter.

4. In a sound reproducing device, a stylus, a stylus arm for holding said stylus adapted Gil to be held in the hand of an operator, a sound box with a diaphragm of high dissipation material driven along a diameter by said stylus arm, stethoscope means for conveying sound vibrations from said sound boX to the ears of said operator, and means for varyin the volume of saidsound vibrations.- k 5. T e combination with a sound pick up'k device having a diaphragm of high dissipationv material and a stylus supportin member attachedV toy the diaphragm for criving it along a diameter, the device being adapted to be held in the hand of an operator, of acous-y tic stethoscopie means for conducting the sound Waves set up in tledviee tothe ears ofthe operator. l y

6; In a: phonograph reprodu'ce'rthe combination of al diaphragmv and a stylus arm attaehed to the diaphragm along a diameter' vof the diaphragm andy adapted to be supported solely between the fingers ofthe operafor and topvot about the point of support. n Y Y 7; The combination with a diaphragm and a stylus 'arm attached to the; diaphragm along a diamete'of the diaphragm. and adapted t'o be supported solely between the; fingers of the operator andv to pvotabout the point of support, of means responsive to vibrations of the diaphragm for directingJ sound' Waves to` the` ears of tlhe' operator.

In witness whereof,k I hereun'to subscribe my name' this 21st dayjof February, 1928.

DAVID' G; BLATTN'ER. 

